The issue was resolved on git-lfs end: https://github.com/git-lfs/git-lfs/issues/4548#issuecomment-879139946

The issue has been addressed on Semaphore 2.0
We are still evaluating the potential solutions for Semaphore Classic.

The problem should be addressed on the git-lfs side soon too.

Due to the ongoing issue with git-lfs package, the apt-get update command is failing on Semaphore.

The issue on the git-lfs repository:
https://github.com/git-lfs/git-lfs/issues/4294#issuecomment-878778071

Our team is working on mitigating this problem and the repository in question will soon be removed from the image.

In the meantime, we suggest this quick workaround for fixing your workflows:

Before running the apt-get update command run the following command in your job:
sudo rm -f /etc/apt/sources.list.d/github_git-lfs.list